Abstract: Apparatus for rotating an annular or ring shape tool such as a saw blade or grinding wheel. The tool is rotated by a power driven drive roller acting on a face of the ting tool. A rigid arm supports guide rollers which in turn support the tool. The guide rollers have grooves that engage the inner periphery of the ring tool. The inner periphery of the ring tool may define a tapered tongue with a rounded edge that fits into complimentary shaped grooves in the guide rollers. Fixed and movable U-shape guards are provided to shield substantially all of the ring tool.